Criminal damage isn't an acquisitive crime. The reason a lot of acquisitive crime is given less attention is because the victim is often a company (i.e. shoplifting) who are generally insured for losses and given lower priority than an actual person. Or insurance such as car insurance, home insurance etc. can foot the bill.

Not saying it's right, in an ideal world we'd be able to treat every single crime with the attention it deserves. But with budgets and resources as stretched as they are it's just not possible and priority has to be given to certain things.

Criminal damage - a keying - would normally be looked into to some extent (definitely if there was any indication it was a hate crime or part of some kind of harassment). However short of CCTV showing who did it, there's not really anything else that can reasonably done. We're not going to get the forensics team out for a scratch on a car, that cost just can't be justified.